One of the objectives of the automotive industry is to simplify component assembly and installation procedures to reduce the time and cost of vehicle assembly. One approach to achieve this goal is to combine components of various vehicle systems into modular assemblies prior to delivering the components to the vehicle assembly line.
Today, many automotive internal combustion engines have a fuel injection system. Fuel pressure regulators are included with these types of fuel systems to control fuel pressure within the fuel rails. It is known in the art to include a fuel pressure regulator downstream of the fuel rail and fuel injectors to provide pressure relief bleeding off excess fuel from the rail back to the fuel tank or reservoir. It is also known in the art to mount this type of fuel pressure regulator on the downstream end of the fuel rail beyond all the fuel injectors. Additionally,.it is also known to provide a demand type fuel pressure regulator upstream of the fuel rail and injectors somewhere in the fuel delivery line.
The demand fuel pressure regulator is used in returnless systems and has a reference line typically connected to either the air intake manifold or to atmosphere. When referenced to the intake manifold, the fuel pressure regulator maintains a constant pressure drop across the injectors. This type of referencing is particularly useful on engines having a turbo charger or supercharger.
The demand type regulator also may be combined with an over pressure relief valve positioned upstream of the regulator between the fuel pump outlet and the regulator inlet for bleeding excess fuel back to the tank. The relief valve opens when the fuel pressure in the rail increases and bleeds back through the regulator during what is known as a hot soak condition or fuel expansion caused by excessive heat accumulated in the fuel rail.